A synthetic memory compound that never reached approval. In animals it restores disrupted learning. Human trials in stroke recovery missed their main goals, and none enrolled healthy adults. Short-term side effects appear acceptable, mainly stomach upset. High-dose animal studies found shrunken testes, poorer sperm, lower testosterone, and kidney and bladder damage. Purity and dose depend on the supplier. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Total testosterone (men) | 600–900 ng/dL | Earliest sensitive marker of the animal testicular lesion |
| Free testosterone (men) | 15–25 pg/mL, or 2.0–3.0% of total | The fraction actually available to tissues |
| Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) | LH 2–6 IU/L; FSH 1.5–8 IU/L | Distinguishes a testicular problem from a pituitary one |
| Estradiol, sensitive assay (men) | 20–30 pg/mL | Rose in dogs while testosterone fell |
| Semen analysis (men) | Concentration >40 million/mL; total sperm number >150 million per ejaculate; motility >50%; normal forms >8% | Direct readout of the endpoint damaged in two animal species |
| Serum creatinine and estimated glomerular filtration rate (eGFR) | eGFR >90 mL/min/1.73 m²; creatinine 0.8–1.1 mg/dL in men, 0.6–0.9 mg/dL in women | Screens for the kidney injury seen in dogs |
| Cystatin C | 0.6–1.0 mg/L | Kidney filtration marker independent of muscle mass |
| First-morning urine osmolality | >600 mOsm/kg | Earliest laboratory sign of the canine papillary lesion |
| Urinalysis with microscopy | Negative for protein and blood | Bladder injury in dogs presented as blood and protein in urine |
| Alanine aminotransferase and aspartate aminotransferase | 10–26 U/L for each | Clearance is almost entirely hepatic |
| Complete blood count | Within conventional reference ranges | General safety screen; no post-marketing surveillance exists |
Cadence: Complete panel before the first dose; reproductive and renal markers at 12 weeks and every 6 months thereafter, with liver enzymes at each draw.